US4376500A - Expandable bag - Google Patents

Abstract

A fluid impervious expandable enclosed bag containing separately compartmented first and second gas generating components which, upon admixture in successive amounts, generate gas causing the bag to expand gradually from a collapsed condition to an ultimately fully expanded condition. The internal compartmentation in the bag also contains a solvent medium and a time release capsule of one of the components, thereby providing apparatus that can be mass produced and used for insertion into aerosol-type liquid product dispensing containers to provide relatively constant expulsion pressure during use.

Description

BACKGROUND OF THE INVENTION

Because of environmental considerations, the substantial increase in the cost of hydrocarbons, the problem of contamination of the dispensed product by the propellant, and the problem of flammability, there has been considerable research and development activity in recent years to find other expulsion means for aerosol-type and other pressurized dispensers.

For many years there have been manual pump-type dispensers, some of which are still in use, and there have been various attempts to use spring-loaded diaphragms and other mechanical means to provide expulsion pressure, but for several reasons each type has had serious deficiencies. Gaseous media other than the usual freon and freon derivatives and homologs, and isobutane/butane mixtures, have also had their drawbacks, e.g., the required useful pressures have either been too high, depending on the compressibility of the gas, and/or constant dispensing pressure over the useful life of the packaged contents was not possible.

Furthermore, as previously mentioned, it is frequently desirable in some applications that the pressure generating medium not mix in direct contact with the product to be dispensed.

One recent development that has apparently solved the above problems and achieved substantial success is the invention disclosed and claimed in U.S. patent application Ser. No. 105,216 filed Dec. 19, 1979 abandoned in favor of continuation application Ser. No. 223,422, filed on Jan. 8, 1981, owned by the common assignee hereof. The latter invention utilizes a flexible enclosed plastic bag containing an envelope attached to the interior walls of the bag and having pockets carrying one of a two-component gas generating mixture therein which are sequentially opened during expansion of the bag to empty the contents into the bag in admixture with the second gas generating components to generate additional gas. The preferred components are citric acid and sodium bicarbonate which in admixture generate carbon dioxide gas.

In said prior application the bag is fabricated at the point of assembling the aerosol can, and water, sodium bicarbonate and a starting capsule or tablet containing an aliquot of the citric acid are inserted, the bag being heat sealed and inserted into the can just prior to filling the can with the product and sealing of the can.

The present invention is a further extension of the latter concept providing greater utility and flexibility in the manufacture of aerosol-type dispensers and permitting the geographical separation of the various manufacturing operations.

BRIEF SUMMARY OF THE INVENTION

The present inventive concept involves a flexible inflatable bag for use as an expulsion means in an aerosol-type fluid product dispenser which can be completely fabricated, ready for use, but transportable to other geographical locations for incorporation into the other dispensing apparatus. The gas generating components, including the solvent medium (e.g. water) and time release starting capsule, are separated in the bag as initially constructed, but readily mixable by appropriate mechanical manipulation of the package at the point of final assembly with said other dispensing apparatus.

Basically, the bag comprises a first group of compartments disposed in the bag in serial alignment containing a first gas generating component such as citric acid, powdered or in a water solution. The compartments are releasably sealed to the internal sidewall of said bag in the collapsed condition. The second component (e.g. sodium bicarbonate) is disposed within the bag external of the first group of compartments. A solvent medium such as water is contained in a separate rupturable separate bag or compartment inside the bag. A time release capsule of the first component is located in the bag, usually adjacent the second component, such that it can be dissolved in the solvent medium when desired to initially activate the gas generating system, i.e., at the point of final assembly of the bag into an aerosol can, and thus brought into admixture with the second component. The first group of compartments is successively unsealable from the sidewall of the bag during expansion of the bag to discharge the first component therein into admixture with the solvent containing the second component, to maintain generation of said gas and a relatively constant pressure thereof until the bag reaches its fully expanded condition.

Such a unitary bag construction permits automatic fabrication and assembly of the bags in a continuous strip of successive bags which can be rolled up and shipped to a final assembly location and sequentially severed, activated and assembled with the other aerosol product and can components by automatic machines.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is an elevational section of a typical aerosol-type container incorporating the bag of the present invention;

FIG. 2 is a sectionalized top plan view of a similar container showing the bag in initial collapsed condition;

FIG. 3 is sectionalized top plan view of the device of FIG. 2 during initial activation of the bag;

FIG. 4 is an enlarged top plan view of one embodiment of the bag;

FIG. 5 is a longitudinal section taken alonglines 5--5 of FIG. 4;

FIG. 6 is a transverse section taken alonglines 6--6 of FIG. 4;

FIG. 7 is an enlarged fragmentary section of the bag showing one of the gas generating component compartments;

FIG. 8 is a schematic flowsheet depicting the assembly steps for fabricating the embodiment of the bag shown on the foregoing figures;

FIG. 9 is a schematic flowsheet depicting the final assembly steps of the bag with the fluid product and the other aerosol can components;

FIG. 10 is an enlarged top plan view of another embodiment of the bag;

FIG. 11 is a longitudinal section taken alonglines 11--11 of FIG. 10;

FIG. 12 is a transverse section taken alonglines 12--12 of FIG. 10; and

FIG. 13 is a schematic flowsheet depicting the assembly steps for fabricating the embodiment of the bag shown in FIGS. 10-12.

DETAILED DESCRIPTION

Referring now to the drawings, one embodiment of the bag assembly according to the present invention is shown in FIGS. 4-6 and designated generally byreference numeral 10.

The bag is comprised ofplastic sheets 11 and 12 which in the embodiment shown are generally rectangular in shape and adhered to one another, e.g., by heat sealing or other conventional methods, at theirrespective margins 13 to provide the sidewalls of the bag-like device with anopen interior 14.

Sheet 11 has a plurality of compartments orrecesses 15 formed therein by vacuum forming or other conventional means, each such recess facing theinner surface 16 of opposite sheet 12 (see FIG. 5).

Recesses 15 are disposed generally longitudinally of saidbag assembly 10 in a staggered fashion at one side thereof and disposed within each such recess in onecomponent 17 of a two-component gas generating system, e.g., citric acid, which can be either in powdered or water solution form, or sodium bicarbonate in powdered or water solution form as desired.Recesses 15 are closed by separateplastic sheet 18 which is releasably adhered tosheet 11 along themarginal areas 19 surrounding said plurality ofrecesses 15 by suitable means such as heat sealing.Sheet 18 on its outer surface, i.e., the surface opposite that in contact withsheet 11, is permanently adhered toinner surface 16 ofouter bag sheet 12 along longitudinal portion orseparation seal 20 andsheet 18 is further adhered tosheet 11 by angular portions or guard seals 20a adjacent respective recesses 15 (see FIG. 4), all such connections designed to provide a sequential opening ofrecesses 15 during use which will be described in detail hereinafter.

A separate, smaller,independent bag 21 is disposed withinlarger bag 10 adjacent the longitudinal side opposite that on whichrecesses 15 are disposed, or to the right as viewed in FIG. 4.Bag 21 is charged with the solvent medium, e.g., water, and is fabricated of suitable, rupturable sheet material for purposes to be described.

At theinterior bottom portion 22 ofbag 10 is disposed secondgas generating component 23, e.g., sodium bicarbonate or citric acid. This component is in dry powdered form. Twotime release capsules 24 containing the same gas generating component as therecesses 15 are also disposed at thebottom portion 22 ofbag 10adjacent component 23.

Bag 10 may be constructed of a flexible, fluid impermeable plastic such as, for example, polyethylene or polypropylene and in one embodiment may be a laminated plastic of low-density polyethylene and polypropylene with optionally one or more intermediate plastic layers of other materials (see FIG. 7). The low-density polyethylene layer may vary from about 0.5 to about 20 mils in thickness and the polypropylene layer from about 0.1 to about 3.75 mils thickness or more.Bag 10 may also be fabricated if desired from foil (e.g., aluminum foil) or from a foil/plastic laminate. The latter composite bag structure is particularly suitable when the present invention is used for dispensing medicines or drugs and the like. Where releasable seals have been mentioned hereinabove, using the laminated polyethylene/polypropylene would involve polypropylene to polyethylene contacting surfaces of the respective sheets involved, i.e., non-homogeneous or incompatible interfaces, and where a permanent seal is required, a polypropylene to polypropylene, or polyethylene to polyethylene, interface is required, i.e., homogeneous or compatible interfaces, all of which is well known to those skilled in the art. Other permanent and releasable sealing methods can be employed by the use of appropriate separate conventional and well-known adhesive compositions, if desired.

While citric acid and sodium bicarbonate have been shown as suitable two-component gas generating (CO₂) components, it is possible that under particular circumstances other components may be used such as diluted hydrochloric acid (e.g., 10-30% up to about 35%) in place of the citric acid and lithium carbonate or calcium carbonate in place of the sodium bicarbonate. Normal operating pressure is, for example, 100 psi, the aerosol can being rated at 180 psi. The operating pressure can be predetermined by the starting charges and concentrations of the two gas generating components and the charges of the one component inrecesses 15. Furthermore, the concentrations of citric acid in therecesses 15 can be varied from recess to recess, e.g., it may be desired to have heavier acid concentrations in the last one or two recesses (at the upper recesses as viewed in FIG. 4).Time release capsules 24 preferably utilize an outer shell material designed to dissolve and expose the internal citric acid within a 3 to 5 minute period with or without external heat being applied to the system to enable starting the initial activation of gas generating components and their assembly ofbag 10 into aerosol can 25 before expansion ofbag 10 begins.

Variations are possible. For example, water pouch orbag 21 may contain the sodium bicarbonate dissolved in the water rather than have the sodium bicarbonate in powder form in thebottom 22 ofbag 10 as described above. On the other hand, thewater bag 21 may contain the startup amount of citric acid dissolved in the water rather than having thestartup capsules 24 in thebottom 22 ofbag 10, in which case time release beaded sodium bicarbonate would be used in thebottom 22 ofbag 10.

Automated assembly ofbag 10 is schematically shown in FIG. 8 whereinplastic sheet 11 is delivered to Station A where thecompartments 15 are formed therein by vacuum forming or the like. The so-formed sheet is then delivered to Station B where thewater pouch 21 is placed onsheet 11 to one side ofrecesses 15 as shown. At Station C, thecitric acid 17 is deposited incompartments 15. At Station D,plastic sheet 18 is releasably adhered tosheet 11 atmargins 19 and angular portions 20a to enclosecompartments 15 and provide assurance that the recesses will be opened one at a time. At Station E, time release capsules are deposited onsheet 11 near oneend 22. At Station F, thesodium bicarbonate powder 23 is deposited onsheet 11. At Station G,top sheet 12 is sealed at its margin tosheet 11 and atportion 20 tosheet 18 providing completedbag assembly 10 ready for utilization.

As shown in FIG. 9, the fabrication ofbag 10 can be effected in acontinuous strip 28 providing a plurality of successive similar bags and incorporated in asupply roll 29 which may be delivered to automatic package assembly equipment shown schematically in FIG. 9. The package containingcontinuous strip 29 is delivered to a first Station A at which the delivery end 30 ofstrip 29 is held at one side byrolls 31 and thefirst bag member 32 is severed by cuttingmeans 33 wherebybag 32 is delivered to receivinghopper 34 disposed overcan body 35. Simultaneously during such operation rolls 31 rupture thewater bag 21 as thebag 32 passes therethrough, thereby delivering water to the bottom ofbag 10 to dissolvecomponent 23 and begin activation oftime release capsules 24.

Hopper 34 opens to deliverbag 32 to the interior ofcan 35 which is then delivered to Station B wherefluid product 36 is introduced intocan 35 by nozzle means 37. At Station C conventional cap means 38 includingaerosol valve assembly 39 are affixed to top 49 ofcan 35. Prior to such sealingperforated tube 41 is inserted in the interior ofcan 35 to prevent expansion ofbag 32 during use all the way to the sides of the can thereby possibly trapping some of theliquid product 36 and preventing dispensing thereof.Means 38 includes perforatedmember 42 to similarly preventbag 32 from blocking theaerosol valve 39. After complete assembly, the fully assembledcontainer 43 is immersed inhot water bath 44, if necessary, to activate the time release capsule and water solution of sodium bicarbonate which initially expands the bag as shown at Station D.

FIGS. 1, 2 and 3 show the overall action of thebag 10 in aerosol can 43 during use. FIG. 1 is the approximate relation of the assembly at initial activation. FIG. 2 shows the bag in its fully collapsed condition prior to activation and FIG. 3 shows the conditions of the bag during the heat activation steps.

Another embodiment ofbag 10 is shown in FIGS. 10-12 and its method of assembly shown in FIG. 13. In this embodiment, in lieu ofwater bag 21, an enlarged recess orcompartment 50 is formed insheet 11 to one side thereof (see FIG. 6) during formation of theother recesses 15 and the solvent orwater 51 is disposed therein. Rupturableplastic cover sheet 52 is heat sealed or otherwise adheredsheet 11 to enclosecompartment 50.

Referring to FIG. 13, the method of assembly of the embodiment ofbag 10 is shown.Sheet 11 is delivered to Station A at which recesses 15 andcompartment 50 are vacuum formed. AtStation B water 51 is added tocompartment 50. At Station Ccitric acid 17 is added to recesses 15. At StationD cover sheet 18 is adhered tosheet 11 at themargins 19 and angular portions 20a to coverrecesses 15 and to provide assurance that therecesses 15 will be opened one at a time. At StationE cover sheet 52 is adhered tosheet 11 to coverwater compartment 50 andcapsules 24 are deposited onsheet 11 near oneend 22 thereof. At StationF sodium bicarbonate 23 is deposited onsheet 11. AtStation G sheet 12 is adhered at its margins tosheet 11, and atportion 20 tosheet 18 to provide fully assembledbag 10.

As can be appreciated from the foregoing description, an expansible, self-contained, pressure generating unit is provided that can be fabricated at one location and conditioned for operation at another location. The unit is easily assembled in a dispensing container and provides a relatively constant dispensing pressure during use without coming into contact with the dispensed material. The container can be oriented in any position without loss of the propellant. No flammability or environmental contamination problems are involved.

When required for specific additional protection of thecavities 15 an additional outer layer of foil or film can be laminated or heat sealed to the outer surface ofsheet 11 to protect the cavities.

While certain embodiments have been shown and described herein, it is to be understood that certain changes can be made by those skilled in the art without departing from the scope and spirit of the invention.

Claims (13)

What is claimed is:

1. A fluid impervious expandable enclosed bag containing separately compartmented first and second gas generating components which, upon admixture in successive amounts, generate gas causing said bag to expand gradually from a collapsed condition to an ultimately fully expanded condition, said bag comprising a plurality of recesses disposed in the sidewall of said bag in serial alignment, said first component disposed in said recesses, a cover sheet enclosing said recesses, said cover sheet releasably adhered to the internal sidewall of said bag adjacent said recesses and permanently adhered to said internal sidewall opposite said recesses, said second component disposed within said bag separate from said recesses, separate container means disposed in said bag and a solvent medium disposed therein, an additional quantity of said first component disposed within said bag separate from said recesses in time release condition, said separate container means rupturable to cause its contents to be discharged into the interior of said bag into admixture with said time release first component and said second component to initiate generation of said gas after a predetermined time interval, said cover sheet being successively releasable from said recesses upon expansion of said bag to discharge the first component therein into admixture with said solvent containing said second component to maintain generation of said gas and a relative constant pressure thereof until said bag reaches its fully expanded condition.

2. A fluid impervious expandable enclosed bag containing separately compartmented first and second gas generating components which, upon admixture in successive amounts, generate gas causing said bag to expand gradually from a collapsed condition to an ultimately fully expanded condition, said bag comprising a plurality of recesses disposed in the sidewall of said bag in serial alignment, said first component disposed in said recesses, a cover sheet enclosing said recesses, said cover sheet releasably adhered to the internal sidewall of said bag adjacent said recesses, and permanently adhered to said internal sidewall opposite said recesses, a separate container means disposed in said bag and a solvent medium and said second component disposed therein, an additional quantity of said first component disposed within said bag separate from said recesses and said container means in time release condition, said separate container means rupturable to cause its contents to be discharged into the interior of said bag into admixture with said time release first component to initiate generation of said gas after a predetermined time interval, said cover sheet being successively releasable from said recesses upon expansion of said bag to discharge the first component therein into admixture with said solvent containing said second component to maintain generation of said gas and a relative constant pressure thereof until said bag reaches its fully expanded condition.

3. A fluid impervious expandable enclosed bag containing separately compartmented first and second gas generating components which, upon admixture in successive amounts, generate gas causing said bag to expand gradually from a collapsed condition to an ultimately fully expanded condition, said bag comprising a first group of compartments disposed in said bag in serial alignment containing said first component and releasably sealed to the internal sidewall of said bag in said collapsed condition, said second component disposed within said bag external of said first group of compartments, a separate compartment disposed within said bag and a solvent medium disposed therein, an additional quantity of said first component disposed within said bag external of said first group of compartments in time release condition, a portion of said separate compartment rupturable to cause its contents to be discharged into the interior of said bag into admixture with said time release first component and said second component to initiate generation of said gas after a predetermined time interval, said first group of compartments being successively unsealable from said sidewall upon expansion of said bag to discharge the first component therein into admixture with said solvent containing said second component to maintain generation of said gas and a relative constant pressure thereof until said bag reaches its fully expanded condition.

4. A fluid impervious expandable enclosed bag containing separately compartmented first and second gas generating components which, upon admixture in successive amounts, generate gas causing said bag to expand gradually from a collapsed condition to an ultimately fully expanded condition, said bag being elongated and comprising a first group of compartments disposed in said bag in serial staggered longitudinal alignment from the interior of said bag toward an outer edge thereof, said compartments containing said first component and being releasably sealed to the internal sidewall of said bag in said collapsed condition, said second component disposed within said bag external of said first group of compartments, a separate compartment disposed within said bag and a solvent medium disposed therein, an additional open compartment disposed within said bag and said first component disposed therein in time release condition, said separate compartment rupturable to cause its contents to be discharged into the interior of said bag into admixture with said time release first component and said second component to initiate generation of said gas after a predetermined time interval, said first group of compartments being successively unsealable from said internal sidewall upon expansion of said bag to discharge the first component therein into admixture with said solvent containing said second component to maintain generation of said gas and a relative constant pressure thereof until said bag reaches its fully expanded condition.

5. In the bag according to claim 4, said first group of compartments comprised of pockets formed in the interior wall of said bag and having openings facing the interior of said bag, said pockets each containing said first component, a plastic sheet releasably enclosing said pockets on one side of said sheet and permanently adhered to the opposed inner wall portion of said bag on the other side of said sheet by a separation seal extending generally longitudinally and centrally of said bag and laterally and inwardly spaced from said pockets, and a plurality of angular guard seals releasably joining said other side of said plastic sheet to said opposed inner wall portion of said bag at locations adjacent said pockets and intermediate said pockets and said separation seal.

6. In the bag according to claim 5, said separate compartment comprised of a pocket formed in the wall of said bag, water disposed in said pocket, and a rupturable sheet enclosing said pocket.

7. In the bag according to claim 6, said additional compartment comprised of a pocket formed in the wall of said bag, and at least one time release capsule containing said first component disposed in said pocket, said capsule adapted to contact said water when said rupturable sheet is broken.

8. In the bag according to claim 7, said first component being citric acid and said second component being sodium bicarbonate.

9. In the bag according to claim 8, said plastic bag being laminated with polyethylene on the exterior wall and polypropylene in the interior wall, and said plastic sheet enclosing said first group of pockets being laminated and having polyethylene on its said one side and polypropylene on its said other side.

10. In the bag according to claim 4, said separate compartment comprising an independent rupturable enclosure containing said solvent medium and said second component.

11. In the bag according to claim 10, said solvent medium comprised of water, said first and second components being citric acid and sodium bicarbonate, respectively.

12. In the bag according to claim 11, said enclosure being comprised of plastic film.

13. In a dispensing container of the type having internal pressure generating means for dispensing a material therefrom upon operation of a dispensing valve means, the improvement comprising a pressure generating means including a fluid impervious expandable enclosed bag containing separately compartmented first and second gas generating components which, upon admixture in successive amounts, generate gas causing said bag to expand gradually from a collapsed condition to an ultimately fully expanded condition, said bag comprising a plurality of recesses disposed in the sidewall of said bag in serial alignment, said first component disposed in said recesses, a cover sheet enclosing said recesses, said cover sheet permanently adhered to said internal sidewall opposite said recesses by an elongated separation seal disposed centrally of said bag and inwardly from said recesses and releasably adhered to the internal sidewall of said bag adjacent said recesses by a plurality of guard seals adjacent said recesses and intermediate of said recesses and said separation seal, said second component disposed within said bag separate from said recesses, separate container means disposed in said bag and a solvent medium disposed therein, an additional quantity of said first component disposed within said bag separate from said recesses in time release condition, said separate container means rupturable to cause its contents to be discharged into the interior of said bag into admixture with said time release first component and said second component to initiate generation of said gas after a predetermined time interval, said cover sheet being successively releasable from said recesses upon expansion of said bag to discharge the first component therein into admixture with said solvent containing said second component to maintain generation of said gas and a relative constant pressure thereof until said bag reaches its fully expanded condition.

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